The cardiovascular system serves to provide the
body with an adequate blood supply. This blood delivers oxygen and nutrients,
hormones, and antibodies to the body’s tissues and removes waste products.
Furthermore, the vascular system also helps to regulate body temperature, fluid
balance, and blood pressure. The cardiovascular system consists of the heart,
blood vessels, and blood.

The heart is a muscular organ with a single
purpose - to pump blood to supply oxygen enriched red blood cells to the tissues
of the body. The heart is divided down the middle into two sides (left and
right) by a wall called the septum. Each side of the heart has an atrium (upper
chamber), and a ventricle (lower chamber). Blood leaves each of the four
chambers of the heart through a one-way valve. These valves keep the blood
moving through the circulatory system in the proper direction. The largest valve
is the aortic valve, lying between the left ventricle and the aorta. The aorta,
the body's main artery, receives the blood ejected from the left ventricle and
delivers it to all the other arteries so that they can carry oxygenated blood to
the tissues of the body.

The right side of the heart receives
deoxygenated blood from the veins of the body. Blood enters into the right
atrium from the vena cavae, which then fill the right ventricle via the
tricuspid valve. During contraction of the right ventricle, blood flows into the
pulmonary artery via the pulmonic semilunar valve and the pulmonary circulation,
where the blood is oxygenated. The left side of the heart receives oxygenated
blood from the lungs through the pulmonary veins. Blood enters into the left
atrium, and then passes into the left ventricle via the mitral or bicuspid
valve. This ventricle of the heart is more muscular than the other because it
must pump blood into the aorta and all the other arteries of the body.

The heart contains more than muscle tissue. The
heart's electrical system, which is distributed throughout the entire heart,
controls heart rate and enables the atria and ventricles to work together.
Normal electrical impulses begin in the sinus node, just above the atria. The
impulses travel across both atria, causing them to contract. Between the atria
and the ventricles, the impulses cross over a bridge of special electrical
tissue called the atrioventricular (AV) node. Here the signal is slowed down for
about one tenth to two tenths of a second to allow blood time to pass from the
atria to the ventricles. The impulses then exit the AV node and spread
throughout both ventricles via the purkinje fibres and the bundle of his,
causing the ventricular muscle cells to contract.

The systemic circulation is composed of
arteries, veins, capillaries and blood. The blood vessels are a closed system of
tubes through which blood flows. Arteries and arterioles take blood away from
the heart. Arteries have three layers and are thicker and stronger than the
other vessels in the body. The middle layer contains smooth muscle and a large
amount of elastic fibers. The two most important properties of the arteries are
elasticity (the ability to stretch) and contractility (the ability to
constrict). The arterial walls become thicker, more muscular, and less elastic
as the arteries branch into smaller vessels (arterioles). This smooth muscle in
the wall of the artery allows for contraction and relaxation of the vessel;
hence vasoconstriction (getting smaller) and vasodilation (getting larger). The
arterial system is a high pressure system and contains about 20% of the systemic
circulation.

The capillaries are distributors. The vessel
walls are composed of a single layer of tissue. This thin wall serves to
facilitate the exchange of gases, nutrients and wastes between the tissues and
the blood supply. The blood flow at this level is slow which also serves to
enhance exchange. Capillaries contain no smooth muscle and therefore lack the
ability to actively vasodilate or vasoconstrict. At the origin of the capillary
is a precapillary sphincter which acts as a stopcock to control the amount of
blood entering the capillary. The capillaries contain about 5% of the systemic
circulation.

The veins are similar to the arteries, in that
they contain the same three layers as the arteries, but when compared to the
arteries they have much thinner walls and fewer elastic fibers. Because of these
characteristics the veins are very distensible. Their diameters change
passively, in response to small changes in internal pressure. Hence, veins are
able to receive large volumes of blood with minimal increases in pressure. The
veins not only act as conduits to channel blood from the capillaries to the
heart, they have the ability to adjust their total capacity to accommodate
variations in the total blood volume. The venous system is a low pressure
system.

About 75% of the blood volume is found in the
venous system. Of this amount, the majority is found in the veins of the
systemic organs (mostly areas like the skin and less essential organs). This
reservoir is largely stored blood and is known as the peripheral venous pool. A
second, similar reservoir is known as the central venous pool and is comprised
of the great veins of the thorax and right atrium. When the peripheral veins
constrict (due to stress or exertion) blood that has been stored in the
peripheral venous pool is mobilized and enters the central venous pool returning
to the heart. This serves to enhance cardiac filling. This system of
distributing the blood volume has important implications for the body when it is
in a shock situation.

Blood is a viscous fluid which is heavier than
water and constitutes about 8% of body weight. Average blood volume in an adult
is between 4 and 6 litres. It serves to transport oxygen, carbon dioxide,
nutrients, waste products, hormones and enzymes. It serves to regulate pH though
buffer systems and protects against toxins and foreign microbes through special
combat cells. Because of the large water content in the blood, it serves to
regulate body temperature and control the water content of the cells. Finally
blood prevents the loss of body fluids through clotting.

Coagulation Cascade

Differences between arterial, venous and
capillary bleeding

Injuries and some illnesses can disrupt blood
vessels and cause bleeding. Typically, bleeding from an open artery is bright
red (high in oxygen) and spurts in time with the pulse. The pressure that causes
the blood to spurt also makes this type of bleeding difficult to control. As the
amount of blood circulating in the body drops so does the patient's blood
pressure.

Blood from an open vein is much darker (low in
oxygen) and flows steadily. Because it is under less pressure most venous blood
does not spurt and is easier to manage. Bleeding from damaged capillary vessels
is dark red and oozes from a wound steadily but slowly. It may clot
spontaneously.

Components and function
of blood:

Plasma

The sticky yellow fluid that carries the
blood cells and nutrients

Transports cellular waste material to the
organs of excretion

It contains most of the compounds needed to
produce a blood clot

Red Blood Cells (Erythrocytes)

The hemoglobin on these cells gives blood
its characteristic red color

Hemoglobin allows the cells to pick up and
transport oxygen to the body tissues and remove about 20% carbon dioxide
from the tissues

White Blood Cells (Leukocytes)

Serve as the defense mechanism of the body,
to combat infection

Produce antibodies

Platelets (Thrombocytes)

Cells in the blood
that are essential in the clotting process

Body Substance Isolation (Routine Practices)

For many years, guidelines have required medical
personnel to take steps to protect themselves against diseases transmitted
through blood. This is known as taking Universal Precautions. More recently the
term Body Substance Isolation (BSI) has been used. BSI is an isolation strategy
designed to prevent the transmission of potential pathogens between patients.
BSI goes a step beyond Universal Precautions and assumes all body substances
potentially infectious. For example, feces, nasal secretions, sputum, sweat,
tears, urine and vomitus would also be considered infectious.

The current term used in Canada is Routine
Practices. Routine Practices integrates the major features of Universal
Precautions and BSI. This strategy applies to blood and all body fluids except
sweat, regardless of whether or not they contain visible blood. Handwashing is
recommended after glove removal regardless of whether or not hands are visibly
soiled.

Pressure points.
If a wound continues to bleed despite use of direct local pressure, you
should elevate the extremity and place additional pressure over a proximal
pulse point. The larger the blood vessel that is involved in the bleed
(injury), the more likely it is that use of a pulse point will need to
occur. A pulse point, or pressure point, is a spot where a blood vessel lies
near a bone. This technique is also useful if you have no material on hand
to use for a dressing. Because a wound usually draws blood from more than
one major artery, proximal compression of a major artery rarely stops
bleeding completely, but it helps to slow the loss of blood. You must be
thoroughly familiar with the location of the pulse points for this to work.

If bleeding persists apply additional
dressings and pressure dressings as needed in layers.

Use a tourniquet when no other methods are
successful (last resort).

Never remove a dressing or pressure dressing
once applied (as it disrupts clot formation).

It is important to estimate blood loss
(whenever possible), taking into consideration soaked towels, pools of
blood, carpet stains, etc.

Application of a Tourniquet

Application of a tourniquet should only be
considered as a last resort in the control of external bleeding.

·Tourniquets may only be used on
extremities.

·Rapid transport to medical care
should be immediately initiated.

·A commercial tourniquet, such
as the SOF-TT, should be used if available.

·The tourniquet should be made
from wide material such as a 7 to 10 centimeter (3-4 inch) wide cravat or a
blood pressure cuff.

·Prior to application distal
circulatory and neurological status must be assessed.

·The tourniquet should be
applied as proximal to the injury site as possible.

·If the injury is anywhere below
the knee, the tourniquet should be applied above the knee just enough to stop
bleeding.

·If a blood pressure cuff is
used it should be inflated to 30 mm Hg above the systolic pressure.

·Bleeding, distal circulation
and neurological status must be re-evaluated after application of the
tourniquet.

Tourniquets have, in the past, been released
for three to five minutes every thirty minutes to allow distal circulation.
Recent studies in the field and in hospital settings have discarded this as
resultant blood loss only contributes to further complications of shock.

·If a tourniquet must be
released prior to arrival at definitive care:

·The first release of the
tourniquet may be done after the tourniquet has been in place for two hours and
then every thirty minutes thereafter.

·Other methods of bleed control
must be used while tourniquet is released (direct pressure, elevation, pressure
points)

·Direct pressure, elevation, and
pressure points should be used to control bleeding during the tourniquet release
time.

·Time of tourniquet application,
any release, and re-application must be documented. Health care staff at the
receiving facility must be aware the patient has a tourniquet in place.

Internal Bleeding and Shock

Internal Bleeding

Internal bleeding can be very serious,
especially because you might not be aware that it is happening. Injury or damage
to internal organs commonly results in extensive internal bleeding, which can
cause hypovolemic shock before you realize the extent of blood loss. A person
with a bleeding stomach ulcer may lose a large amount of blood very quickly.
Similarly, a person who has a lacerated liver or a ruptured spleen may lose a
considerable amount of blood within the abdomen. Yet, the patient has no outward
signs of bleeding. Broken bones, especially broken ribs, also may cause serious
internal blood loss.

Sometimes this bleeding extends into the chest
cavity and the soft tissues of the chest wall. A broken femur can easily result
in the loss of 1L or more of blood into the soft tissues of the thigh. Often,
the only signs of such bleeding are local swelling and bruising due to the
accumulation of blood around the ends of the broken bone.

You must always be alert to the possibility of
internal bleeding and assess the patient for related signs and symptoms,
particularly if the mechanism of injury is severe. If you suspect that a patient
is bleeding internally, you should promptly transport him or her to the
hospital.

Mechanism of Injury

Internal bleeding is possible whenever the
mechanism of injury suggests that severe forces affected the abdomen and/or the
chest. These forces include rapid acceleration, rapid deceleration, shearing, or
compression. Internal bleeding commonly occurs as a result of falls, blast
injuries, and automobile or motorcycle crashes, whether the patient is a
pedestrian, driver, or passenger.

As you assess a patient, look for signs of
injury over the chest or abdomen, including contusions, abrasions, lacerations,
or other signs of injury or deformity. You should always suspect internal
bleeding in a patient who has a penetrating injury, such as a knife or gunshot
wound.

Nature of Illness

Non-traumatic internal bleeding can lead to
shock just as easily as bleeding caused by trauma. Internal bleeding can occur
in the abdomen as a result of inflammatory bowel disease, an aneurysm, a
ruptured ectopic pregnancy, or other medical conditions.

Abdominal pain and distention are common in
these situations but are not always present. In older patients, dizziness,
faintness, or weakness may be the first sign of non-traumatic internal bleeding.
Ulcers or other gastrointestinal problems may cause vomiting of blood or bloody
diarrhea.

It is not as important for you to know the
specific organ or condition involved as it is to recognize that the patient is
in shock and respond appropriately.

Signs and Symptoms

The most common symptom of internal abdominal
bleeding is acute abdominal pain. Another common sign is bruising around the
abdomen. This can occur with or without trauma. Bruising is also called
contusion or ecchymosis. A hematoma, a mass of blood in the soft tissues beneath
the skin, indicates bleeding into soft tissues and may be the result of either a
minor or a severe injury.

Bleeding, however slight, from any body opening
is serious. It usually indicates internal bleeding that is not easy to see or
control. Bright red bleeding from the mouth, or rectum, or blood in the urine (hematuria)
may suggest serious internal injury or disease. Non-menstrual vaginal bleeding
is always significant.

Other signs and symptoms of internal bleeding in
both trauma and medical patients include the following:

Hematemesis. This is vomited blood. It may be bright red
or dark red, or if the blood has been partially digested, it may look like
coffee ground vomitus.

Melena. This is a black, foul-smelling, tarry stool
that contains digested blood.

Hemoptysis. This is bright red blood that is coughed up
by the patient.

The following signs and symptoms may mean that a
closed fracture is causing bleeding.

Pain, tenderness, bruising, or swelling.

Bruises over the lower chest, or a rigid,
distended abdomen.

In addition to the previously listed signs and
symptoms, the following may indicate a lacerated spleen or liver. Patients with
an injury to either organ may have referred pain in the right shoulder (liver)
or left shoulder (spleen). You should suspect internal abdominal bleeding in a
patient with referred pain.

The first sign of hypovolemic shock (hypoperfusion)
is a change in mental status, such as anxiety, restlessness, or combativeness.
In non-trauma patients, weakness, faintness, or dizziness on standing is another
early sign. Changes in skin color, or pallor, are seen often in both trauma and
medical patients. Later signs of hypoperfusion suggesting internal bleeding
include the following:

Tachycardia

Weakness, fainting, or dizziness at rest

Thirst

Nausea and vomiting

Cool, moist (clammy) skin

Shallow, rapid breathing

Dull eyes

Slightly dilated pupils that are slow to
respond to light (sluggish)

Capillary refill in infants and children of
more than 2 seconds

Weak, rapid (thready) pulse

Decreasing blood pressure

Altered level of consciousness

Casualties with these signs and symptoms are at
risk. Some may be in danger. Even if their

bleeding stops, it could begin again at any
moment. It could also be a sign their blood volume is too low to bleed anymore.
Therefore, prompt transport is necessary.

Emergency Care

Controlling internal bleeding or bleeding from
the major organs usually requires surgery or other procedures that must be done
in the hospital. The main responder role in these cases is to keep the patient
still to promote clot formation and to provide high-flow oxygen and prompt
transport. However, you can usually control internal bleeding of the extremities
by splinting the extremity. You should never use a tourniquet to control the
bleeding from closed, internal, soft-tissue injuries.

Follow these steps to care for casualties with
possible internal bleeding:

Follow BSI techniques.

Maintain the airway with cervical spine
immobilization if the mechanism of injury suggests the possibility of spinal
injury.

Treat suspected internal bleeding in an
extremity by applying a splint.

Monitor and record the vital signs at least
every 5 minutes.

Give the casualty nothing (not even small
sips of water) by mouth.

Keep the casualty warm.

Provide immediate transport for all
casualties with signs and symptoms of shock (hypoperfusion).

Shock

Shock – An abnormal condition of inadequate
blood flow to the body’s peripheral tissues associated with life threatening
cellular dysfunction: also known as Hypoperfusion.

The Pathophysiological Progression of Shock

The shock state progresses through three stages.

The Compensatory Stage

The Decompensated (Progressive) Stage

The Irreversible (Refractory) Stage

The Compensatory Stage

In this stage cardiac output is decreased. To
combat this and to restore cardiac output, the body activates compensatory
mechanisms. These mechanisms are nervous, hormonal, and chemical.

Within seconds of detecting the loss of cardiac
output, the brain activates the sympathetic branch of the autonomic nervous
system. The heart is stimulated to beat faster and harder. Blood vessels to the
essential organs i.e.; heart, brain etc. are vasodilated to increase their blood
supply. Blood vessels going to non essential areas such as the skin, digestive
tract, and kidneys are vasoconstricted to shunt blood to priority organs.

As a follow up to the activation of the
sympathetic nervous system, the body releases potent chemicals in an attempt to
restore cardiac output. The adrenal glands release epinephrine which causes
potent vasoconstriction of both veins and arteries. This vasoconstriction
increases blood pressure and facilitates venous return to the right side of the
heart.

To summarize, in the compensatory stage of
shock, the body recognizes it has a problem and initiates compensatory
sympathetic mechanisms in an attempt to maintain cardiac output.

Clinical Findings in Compensatory Shock

Blood Pressure - the blood pressure may be normal with possibly
an elevated diastolic reading due to systemic arteriolar vasoconstriction
(systolic may also be increased in end stage compensatory shock).

Heart Rate - the heart rate is increased because of
sympathetic stimulation. A sinus tachycardia occurs. Depending on the degree of
shock and compensatory mechanisms a heart rate of 100 to 150 could be expected.

Skin - the skin is cool, pale, and clammy as a result
of peripheral vasoconstriction and increased sweat gland activity.

Level of Consciousness - as the patient enters into the compensatory
phase the patient may be restless and anxious. In the latter phase of the
compensatory stage the level of consciousness may decrease due to decreased
blood supply to the brain. The patient may present as confused and lethargic.

Respirations - may be rapid and shallow with a rate up to two
times the normal.

Pupils - may be dilated, but will react to light.

The Decompensated (Progressive) Stage

If the shock is not reversed during the
compensatory phase the mechanisms initiated during the compensatory stage to
restore the cardiac output begin to have detrimental effects on the patient.
This is due to the fact that prolonged and severe vasoconstriction has adverse
effects on cellular function, capillary dynamics and specific organ systems.

Because of arteriolar vasoconstriction capillary
blood flow is decreased, and oxygen delivery to the cells is reduced. This
results in build up and eventual release of toxins from the cells into the
tissue. With these toxic changes in the tissue environment, the precapillary
sphincters open causing a fluid shift from the vascular compartment into the
cellular beds. The end result is a loss of circulating blood volume that results
in decreased venous return and reduced cardiac output. The patient further
deteriorates, but no significant permanent damage is done if treated promptly
and reversed.

Clinical Findings in Decompensated Shock

Blood Pressure - the blood pressure begins to plummet. The
pulse pressure (the difference between the diastolic and systolic pressures)
decreases (<30 mmHg is significant warning).

Heart Rate - the heart rate continues to increase and may
exceed 150 beats per minute. Peripheral pulses will be rapid and thready and may
in fact be absent.

Skin - the skin will be cold and clammy and in
specific areas (lips, ear lobes, and nail beds) it may be cyanotic.

Level of Consciousness - the level of consciousness is severely
altered. The patient may present with bizarre, inappropriate behavior or may be
lethargic and unresponsive.

Respirations - the patient will be obviously short of breath
and the respirations will be shallow.

Pupils - the pupils will be dilated and sluggish to
react.

The Irreversible Stage

The irreversible stage is often referred to as
the refractory or end stage shock. In this phase the patient has failed to
respond to any form of therapy and is pre-cardiac arrest. Cells have begun to
die and downward spiral begins. Cell death = organ death = organ failure =
system failure = death. Once a patient reaches this stage of shock, permanent
damage and most likely death occurs.

Clinical Findings of Irreversible Shock

Blood Pressure - except for brief periods the patient will not
sustain any blood pressure.

Heart Rate - patient will have no peripheral pulses and the
rate could be fast, slow, or irregular.

Skin - will be cold, cyanosed, or mottled.

Level of Consciousness - patient will be unconscious and unresponsive

Respirations - may be slow, deep, rapid and shallow,
irregular or even absent.

Pupils - will be fixed and dilated.

General Management for Shock

Assessments and management of shock uses the
following guidelines. Special considerations are included in the specific
classification of shock.

Personal protective equipment should be
utilized as appropriate.

Body substance isolation techniques and
equipment should be utilized as appropriate.

Perform a primary survey.

If trained, administer high concentration
oxygen by non-rebreather mask.

Control external bleeding.

Arrange rapid transport to a medical
facility.

Obtain as thorough a history as possible.

Handle the patient gently.

Prevent the loss of body heat.

Perform a secondary survey.

Position the patient in the supine position.

The casualty must be monitored closely for
respiratory compromise, vomiting or

regurgitation.

Treat any injuries.

Repeat and record vital signs at regular
intervals (5-15 mins.) or when there is a change in the casualty's status.

Do not allow the casualty to exert
him/herself, e.g. walking, standing unassisted to a stretcher.

Reassure the casualty. Give nothing by
mouth.

Assist ventilations if required.

Report all findings to medical staff.

General Signs of Shock

Pale, cool, clammy skin

Increase BP developing to decrease BP

Weak, tachycardic pulse

Shallow, tachypnea

Altered LOC (anxiety, fear, restlessness,
confusion, sudden LOC)

Thirst

Cyanosis

Weak, absent radial pulse

Dilated pupils, eyes not focusing

The Classification of Shock

There are many classifications models for shock.
For the purpose of this discussion we will identify five.

Hypovolemic Shock

Cardiogenic Shock

Neurogenic Shock

Septic Shock

Anaphylactic Shock

Hypovolemic Shock

Hypovolemic shock is an emergent condition in
which severe blood and/or fluid loss makes the heart unable to present enough
blood to the body. It develops when the intravascular blood volume is decreased
in relation to the size of the intravascular compartment (ie: veins and
arteries). Hypovolemic shock is usually associated with volume deficits in
excess of 15%. Losses of blood volume can either be internal or external.
Internal losses may be associated with such events as G.I. bleeds, AAA’s, or
internal hemorrhages secondary to trauma.

External losses are associated with blood loss
(most common), in the case of trauma and bleeding disorders; plasma, in the case
of burns; body fluid, in the case of excessive perspiration, vomiting, and
diarrhea. The pathophysiology of hypovolemic shock is that when the
intravascular volume is reduced, venous return is reduced, cardiac output
decreases, and the blood pressure drops. The end result is poor tissue perfusion
which can lead to organ failure.

Signs and symptoms of hypovolemic shock may
include:

tachycardia

altered mental status

delayed capillary refill

skin tenting

dry mouth and mucous membranes

It may be triggered by events other than the
loss of blood and may be due to other fluid or plasma loss.

vomiting or diarrhea

plasma loss due to burns

diabetic ketoacidosis

It may also develop from blood loss not visible
to external assessment. Examples of this hidden blood loss may include:

aneurysm rupture

ectopic pregnancy

internal bleeding

AAA

GI bleed

Mechanisms of injury and thorough history
assessment may provide information on the development of hidden hemorrhagic
shock.

Cardiogenic Shock

Cardiogenic shock is due to the impaired ability
of the heart to pump the blood. Cardiogenic shock is usually the result of
severe left ventricular failure, secondary to acute myocardial infarction or
congestive heart failure. The hypotension that accompanies this form of shock
aggravates the situation by decreasing coronary perfusion. With decreased
coronary perfusion, the heart muscle becomes even more damaged, thus
establishing a vicious cycle that ultimately results in complete pump failure.

Other causes of cardiogenic shock are:

pericardial tamponade

tension Pneumothorax

penetrating trauma to heart

SVC pressure (pregnant women)

During cardiogenic shock, the activation of
compensatory mechanisms can actually worsen the situation. When the peripheral
resistance increases in an attempt to maintain blood pressure, the myocardial
workload increases. This, in turn, increases the myocardial oxygen demand,
further aggravating myocardial ischemia and infarction. Cardiac output is
further depressed.

While the most common cause of cardiogenic shock
is severe left ventricular failure, a number of other factors can have the same
clinical manifestation. These include chronic progressive heart disease, such as
cardiomyopathy, rupture of the papillary heart muscles or interventricular
septum, and end-stage valvular disease (mitral stenosis or aortic
regurgitation). Most patients who experience cardiogenic shock will have normal
blood volume. However, some casualties will be hypovolemic from an excessive use
of prescribed diuretics or the severe diaphoresis that accompanies some acute
cardiac events. Casualties may also experience relative hypovolemia (neurogenic
shock) from the vasodilatory (blood vessel dilation) effects of drugs such as
nitroglycerin.

Signs and symptoms of cardiogenic shock may
include:

Evidence of pulmonary edema on chest
auscultation

Frothy sputum

The casualty may be in an upright position,
using accessory muscles of respiration

weak, rapid or irregular pulse

Peripheral edema may be present in dependent
extremities

Past medical history may include cardiac,
respiratory, renal disease or recent chest trauma.

Neurogenic shock may be described as inadequate
peripheral resistance due to widespread vasodilation. With this inappropriate
vasodilation, a disproportionate amount of blood collects in the capillary bed.
This reduces venous return, cardiac output, and arterial blood pressure.

Neurogenic shock is most commonly due to an
injury that results in severe spinal cord injury or total transection of the
cord. Other causes of neurogenic shock include: central nervous system injury,
septicemia from bacterial infection, anaphylactic reaction, insulin overdose,
and Addisonian crisis (a disorder of the adrenal glands). In neurogenic shock
there is an absence of the sympathetic response. Always suspect neurogenic shock
with spinal injuries.

Be prepared to assist ventilations due to
loss of respiratory muscle function.

Manage as per general shock treatment
guidelines.

Septic Shock

This condition is a type of shock that
accompanies a bacterial infection and is often due to the release of endotoxins
(poisons) by the bacteria or infected tissues. The toxins are carried by the
blood to non-infected areas until the whole body is affected. The toxins then
damage the vessel walls throughout the body, causing them to become leaky and
unable to constrict well.

Widespread dilation of vessels, in combination
with the loss of plasma through the injured vessel walls, results in shock.
Septic shock is a complex problem. First, there is an insufficient volume of
fluid in the container, because much of the blood has leaked out of the vascular
system into the interstitial spaces (hypovolemia). Second, the fluid that has
leaked out often collects in the respiratory system, interfering with
ventilation. Third, there is a larger-than-normal vascular bed (due to systemic
vasodilation) to contain the smaller-than-normal volume of intravascular fluid.
Septic shock is almost always a complication of some very serious illness,
injury or surgery.

Signs and symptoms include:

Warm skin (cool extremities)

Tachycardia

Low blood pressure

Low urine output

Anaphylactic shock

Anaphylaxis, or anaphylactic shock, occurs when
a person reacts violently to a substance to which he or she has been sensitized.
Sensitization means becoming sensitive to a substance that did not initially
cause a reaction. Do not be misled by a patient who reports no history of
allergic reaction to a substance on first or second exposure. Each subsequent
exposure after sensitization tends to produce a more severe reaction.
Anaphylaxis is a true medical, life-threatening emergency.

Instances that cause severe allergic reactions
commonly fall into the following four categories:

Injections (tetanus antitoxin, penicillin)

Stings (honeybee, wasp, yellow jacket,
hornet)

Ingestion (shellfish, oral penicillin)

Inhalation (dusts, pollens)

Anaphylactic reactions can develop in minutes or
even seconds after contact with the substance to which the patient is allergic.
The signs of such allergic reactions are very distinct and not seen with other
forms of shock. In anaphylactic shock, there is no loss of blood, no vascular
damage, and only a slight possibility of direct cardiac muscular injury.
Instead, there is widespread vascular dilation. The combination of poor
oxygenation and poor perfusion in anaphylactic shock may easily prove fatal.

Signs and symptoms:

Skin:

Flushing, itching, or burning, especially
over the face and upper chest

Urticaria (hives), which may spread over
large areas of the body

Edema, especially of the face, tongue, and
lips

Cyanosis (a bluish cast to the skin
resulting from poor oxygenation of circulating blood) of the lips

Circulatory System:

Dilation of peripheral blood vessels (warm,
flushed extremities)

A drop in blood pressure

A weak, barely palpable pulse

Pallor

Dizziness

Fainting and coma

Respiratory:

Sneezing or itching in the nasal passages

Tightness in the chest, with a persistent
dry cough

Wheezing and dyspnea, or difficulty in
breathing

Secretions of fluid and mucus into the
bronchial passages, alveoli, and lung tissue, causing coughing

Constriction of the bronchi; difficulty
drawing air into the lungs

Forced expiration, requiring exertion and
accompanied by wheezing

Cessation of breathing

Anaphylactic shock is a true emergency. If the
casualty has an epinephrine autoinjector, assist them to use it. High
concentrations of oxygen should be delivered to the casualty if you are trained.
Be prepared to support respiratory and circulatory functions.